Additive mixture for the bactericidal and anticorrosive additization of fuels

ABSTRACT

An additive mixture for fuels including a) at least one N-formal, b) at least one antioxidant and c) at least one corrosion inhibitor. The additive mixture ensures that the additized fuels and lubricants have biocidal and corrosion-inhibiting additization, especially when they include proportions of renewable raw materials, such as biodiesel, and when they are in contact with copper-containing surfaces.

The invention relates to an additive mixture for the bactericidal andanticorrosive additization of fuels. The additive can be formulated as aliquid concentrate or as a semiconcentrate. The invention furtherrelates to the use of the additive mixture for bactericidal andanticorrosive additization of fuels, and to correspondingly additizedfuels. The invention also relates to a method for operating a systemwith a fuel which comprises the components of the inventive additivemixture.

In systems which come into contact with fuels (such as heating oil)(storage tanks, conduits, valves, filters, probes, measuringinstruments, burners, etc.), different materials are used, for exampleplastics, metals and alloys, especially copper-containing materials.Owing to the interaction of long storage times, different compositionsof the fuel and external influences such as formation of water ofcondensation, and oxidative and/or microbial degradation processes, thecomposition of the fuel can change and lead to undesired consequentphenomena. These consequent phenomena include corrosion, turbidity up toand including precipitation (formation of “sludge”), blockage of filtersand material wear. This can lead to failure of the system and to thenecessity of expensive repairs. Similar problems arise infuel-processing systems such as stationary and mobile diesel engines andthe corresponding injection systems.

The prior art discloses biocidal compositions for fuels. For example, DE103 40 830 A1 describes compositions based on formaldehyde depotcompounds and antioxidants, and the use thereof for preservingindustrial products, for example fuels. An illustrative formaldehydedepot compound is N,N′-methylenebis(5-methyloxazolidine), which is soldby Schülke & Mayr GmbH (Norderstedt, Federal Republic of Germany) asGrotan® OX (Grotamar® 71, Mar® 71). The compositions have very goodstorability as concentrates and have a constantly low level ofdeformation of the plastic vessel containing the concentrate (“neck-ineffect”).

DE 199 61 621 A1 relates to compositions which comprise a bactericidalN-formal, a fungicide and a stabilizer, for use, for example, in fueladditives. The compositions are storage-stable and have goodmeterability.

In the systems mentioned, as well as fossil fuels such as mineral oil,biofuels (such as biodiesel) are increasingly being used, which comprisefatty acid alkyl esters such as fatty acid methyl esters (FAME), forexample rapeseed oil methyl ester (RME). This is both because of legalstipulations and financial support and because of the insight that, inthe generation of energy from renewable raw materials, the release ofCO₂ is climate-neutral. Since the use of biofuels, however, there hasbeen a significant increase in material compatibility problems. It isassumed that biodiesel, for example, leaches copper ions out ofcopper-containing constituents of the systems. The increased copper ioncontent in turn accelerates the decomposition of the biodiesel andultimately leads to the problems mentioned above.

WO2009/060057 A2 relates to the use of water-soluble biocides inbiodiesel. An example of a biocide is3,3′-methylenebis(5-methyloxazolidine). To improve the efficacy of thebiocides, ethers are proposed. The ethers according to WO2009/060057 A2are needed in a certain amount to dissolve the biocides in thebiodiesel. However, ethers readily form peroxides which can convertconstituents in biodiesel, inactivate antioxidants and wear awaymaterial. The biocidal activity of ethers, moreover, is not comparableto that of formaldehyde depot compounds, and therefore (also asboosters) have to be used at a higher concentration and are thereforeuneconomic. Moreover, ethers have a comparatively low flashpoint and canlead to less favorable labelling of products.

For this reason, it is desirable to add to the fuel improved additiveswhich suppress these troublesome influences (decomposition of thebiodiesel, formation of sludge) or do not allow them to arise at all,without necessarily needing to use ethers. More particularly, it was anobject of the present invention to provide additive mixtures which aresuitable for biocidal and anticorrosive additization of those fuelswhich comprise proportions of renewable raw materials, for examplebiodiesel. The additive mixtures should also be stable as concentratesand be easy to dose.

It has now been found that, surprisingly, these objects are achieved byan additive mixture which comprises

-   -   a) at least one N-formal,    -   b) at least one antioxidant and    -   c) at least one corrosion inhibitor.

Inventive additives protect fuels to which they are added frominfestation by bacteria, yeasts and moulds, and at the same time providethem with the necessary corrosion protection. The advantages of theadditive mixtures are found more particularly in the case of addition tofuels which comprise components composed of renewable raw materials, forexample biodiesel.

a) N-Formal

Inventive additive mixtures comprise at least one N-formal. Theadvantages of these active microbicidal ingredients are disclosed in DE103 40 830 A1. Particularly suitable N-formals are reaction products offormaldehyde and amines (preferably alkanolamines) with a molarformaldehyde excess.

Examples of N-formals are condensation products of paraformaldehyde andisopropanolamine in a molar ratio of 3:2, condensation products ofparaformaldehyde and isopropanolamine in a molar ratio of 3:2 and urea,and condensation products of paraformaldehyde and isopropanolamine in amolar ratio of 3:2 and urea and ethylene glycol.

N-Formals which are used with preference in accordance with theinvention are N,N′-methylenebis(5-methyloxazolidine),α,α′,α″-trimethyl-1,3,5-triazine-1,3,5-(2H,4H,6H)triethanol,4,4-dimethyloxazolidine, dimethylolurea,5-ethyl-3,7-dioxa-1-azabicyclo[3.3.0]octane,2-(hydroxymethylamino)ethanol, methylenebistetrahydro-1,3-bisoxazine,5-methylolchloro-acetamide, bis(hydroxymethyl)-5,5-dimethylhydantoin,diazolidinylurea, sodium hydroxymethylglycinate and3,4,4-trimethyloxazolidine,2,2′,2″-(hexahydro-1,3,5-triazine-1,3,5-triyl)triethanol (Grotan® BK),tetrahydro-1,3,4,6-tetrakis(hydroxylmethyl)imidazo[4,5-d]imidazole-2,5-(1H,3H)dione(TMAD) and tetramethylolglycoluril.

Preference is given to low-water formaldehyde depot compounds.

Particular preferred formaldehyde depot compounds are3,3′-methylenebis(5-methyloxazolidine),2,2′,2″-(hexahydro-1,3,5-triazine-1,3,5-triyl)-triethanol,α,α′,α″-trimethyl-1,3,5-triazine-(2H,4H,6H)triethanol,tetrahydro-1,3,4,6-tetrakis(hydroxymethyl)imidazo[4,5-d]imidazole-2,5(1H,3H)-dione,dimethylurea and the products Grotan OF(methylenebis(5-methyloxazolidine)+urea) and Grotan OK(methylenebis(5-methyloxazolidine)+urea+ethylene glycol).

A very particularly preferred formaldehyde depot compound is3,3′-methylenebis(5-methyloxazolidine).

b) Antioxidant

The inventive additive mixture comprises at least one antioxidant.Preferred antioxidants are liquid or are sufficiently soluble in theformaldehyde depot compound at room temperature. Examples ofantioxidants are selected from sterically hindered phenols, amines,vitamin E and derivatives thereof, and alkyl gallates, preferably3-tert-butyl-4-hydroxyanisole (BHA), 2,6-di-tert-butyl-p-cresol (BHT),2,6-di-tert-butylphenol, lauryl gallate and vitamin E.

Especially preferred as antioxidants are 2,6-di-tert-butylphenol andBHT.

c) Corrosion Inhibitor

The inventive additive mixture comprises, as a further obligatorycomponent c), at least one corrosion inhibitor. Preferred corrosioninhibitors are liquid or are sufficiently soluble in the formaldehydedepot compound at room temperature. Particularly preferred corrosioninhibitors are triazole derivatives, for example benzotriazole,tolyltriazole or N,N-bis(2-ethylhexyl)((1,2,4-triazol-1-yl)methyl)amine.

Particular preference is given to usingN,N-bis(2-ethylhexyl)((1,2,4-triazol-1-yl)methyl)amine, which issupplied by BASF SE (Ludwigshafen, Federal Republic of Germany) asIrgamet® 30.

Amounts of Components a), b) and c)

In additive mixtures preferred in accordance with the invention, theweight ratio of component b) to component c) is typically 20:1 to 1:20,preferably 1:10 to 10:1, especially 1:4 to 4:1, for example 1:1.

As explained hereinafter, inventive additives are typically formulatedas liquid concentrates or semiconcentrates.

Liquid Concentrate

In inventive additive mixtures formulated as liquid concentrates, theproportion of component a) is preferably at least 60% by weight,preferably at least 80% by weight, especially at least 90% by weight,for instance 92% by weight. The proportions of components b) and c) aretypically each at least 0.5% by weight, preferably at least 1% byweight, especially at least 2 by weight, for instance 4% by weight.Particular preference is given to liquid concentrates which consist ofcomponents a), b) and c), i.e. comprise no further constituents.

A particularly preferred liquid concentrate consists of:

-   -   a) 92% by weight of 3,3′-methylenebis(5-methyloxazolidine),    -   b) 4% by weight of 2,6-di-tert-butylphenol and    -   c) 4% by weight of Irgamet 30.

The liquid concentrate is prepared by initially charging component a)(for example 3,3′-methylenebis(5-methyloxazolidine)) and then dissolvingcomponent b) (such as 2,6-di-tert-butylphenol or BHT) and component c)(such as Irgamet 30) while stirring. The product is clear and colourlessto pale yellow.

Inventive liquid concentrates are used prophylactically in fuels whichare yet to be microbially infested in concentrations of 20 to 100 mg/l(ppm), and in fuels which have already been contaminated in amounts of200 to 1000 ppm.

Semiconcentrate

In inventive additive mixtures which have been formulated as asemiconcentrate, the proportion of component a) is typically at least 5%by weight, preferably at least, preferably at least 10% by weight,especially at least 15% by weight, for instance 20% by weight.Components b) and c) are typically present in an amount of in each caseat least 0.1% by weight, preferably at least 0.25% by weight, especiallyat least 0.5% by weight, for instance 0.9% by weight.

Semiconcentrates comprise, as well as the inventive components a), b)and c), a carrier. Examples of carriers are selected from diesel oil,biodiesel oil, fatty acid methyl esters, mineral oil (e.g. Shellsol A150), aliphatic or aromatic hydrocarbons (such as toluene),alkylbenzenes, for example Marlican (RG), and mixtures thereof. Theamount of the carrier in the concentrate is preferably at least 50% byweight, more preferably at least 60% by weight, especially at least 70%by weight, for instance 78% by weight.

A particularly preferred semiconcentrate comprises:

-   -   a) 20% by weight of 3,3′-methylenebis(5-methyloxazolidine),    -   b) 0.9% by weight of 2,6-di-tert-butylphenol    -   c) 0.9% by weight of Irgamet 30        and, as the remainder, a hydrocarbon as a carrier which is        soluble in FAME-containing hydrocarbons, for example diesel        fuel. For example, the carriers used are, for example, ShellSol        A 150 or alkylbenzene (Marlican).

To prepare the semiconcentrate, the carrier is initially charged andcomponent a) (such as 3,3′-methylenebis(5-methyloxazolidine)), componentb) (such as 2,6-di-tert-butylphenol or BHT) and component c) (such asIrgamet 30) are dissolved while stirring. The product is clear andcolourless to pale yellow.

Inventive semiconcentrates are used prophylactically in fuels which areyet to be microbially infested in concentrations of 100 to 500 ppm, andin fuels which have already been contaminated in amounts of 1000 to 5000ppm.

The invention further relates to the use of the inventive additivemixture for biocidal and anticorrosive additization of fuels, and to theprotection thereof from oxidative degradation.

According to the invention, the corrosion of copper in particular as aconstituent of the materials of systems through which the fuel flows orin which it is stored. As mentioned above, the corrosion of copperpresented a problem especially when the fuel comprises proportions ofrenewable raw materials, for example FAME. The proportion of renewableraw materials (such as FAME) which is typically present in the fuel isup to 100% by volume, preferably up to 20% by volume, especially up to10% by volume, such as 5 to 7% by volume.

According to the invention, components a), b) and c) are used in thefuel in an amount which ensures effective protection from microbialattack and from oxidative and corrosive influences. In the fuel, theproportion of component a) should be at least 5 ppm, more preferably atleast 100 ppm and especially preferably at least 200 ppm, for example500 ppm. The proportions of components b) and c) should each be at least0.25 ppm, preferably at least 5 pmm and more preferably at least 10 ppm,for example 25 ppm.

The invention further relates to the use of the inventive liquidconcentrate for producing a semiconcentrate.

Components a), b) and c) are used—in combination—in fuels, preferably inthe form of the inventive liquid concentrates or semiconcentrates. Theyare used in accordance with the invention in lubricants, coolinglubricant concentrates and emulsions, transformer oils, fuels, biofuels,biodiesels, diesel fuels, kerosenes, heavy oils, heating oils, mineraloils, all of which are referred to here as fuels. They are preferablyused in fuels with proportion of material composed of renewable rawmaterials, especially biodiesel.

The inventive formulations can be combined with further active biocidalingredients, functional additives and auxiliaries, as disclosed, forexample, in WO2009/060057 A2, DE 10 2006 035013 A1 or DE 103 40 830 A1.

The combination of components a), b) and c) is used in fuels preferablyby adding a liquid concentrate or a semiconcentrate. Alternatively, itis possible to add components a), b) and c) individually, but thisalternative is not preferred.

The invention further relates to a method for operating a system with afuel, in which the additive mixture described is added to the fuel, orin which the components are added individually.

The invention also relates to a fuel which comprises components a), b)and c) in such an amount that the concentration (based in each case onthe fuel)

-   -   of component a) is at least 5 ppm, preferably at least 100 ppm        and especially at least 200 ppm, for instance 500 ppm;    -   of component b) is at least 0.25 ppm, preferably at least 5 ppm        and especially at least 10 ppm, for instance 25 ppm; and    -   of component c) is at least 0.25 ppm, preferably at least 5 pmm        and especially at least 10 ppm, for instance 25 ppm.

The inventive liquid concentrates or semiconcentrates have the followingadvantages:

-   -   they are clear, homogeneous, fluid, low-viscosity, free-flowing,        low-odour, readily distributable, readily incorporable, possess        good stability (cold stability, storage stability, sufficient        thermal stability) and are easy to handle;    -   they have a broad profile of action: they are bactericidally,        fungicidally and algicidally active, protect from oxidative        degradation, give a good coating on the surfaces to be treated,        protect from corrosion, especially in the case of nonferrous        metals;    -   they protect systems and materials which come into contact with        fuels, especially biofuels;    -   they effectively prevent sludge formation in fuel systems and        vessels;    -   they improve the shelf life of the treated products;    -   they improve the lubricant properties of the treated products;    -   they possess good compatibility with a multitude of materials;    -   they have good solubility in different bases, such as oils;    -   they possess good dissolution capacity for further/additional        additives;    -   no additional solvents are required and    -   they enhance the calorific value of heating oil.

The advantages of the invention are evident more particularly from theexamples which follow.

EXAMPLES

Unless stated otherwise, all percentages are based on weight.

Example 1 Materials Used

-   3,3′-methylenebis(5-methyloxazolidine)-   brass 63 (100×20×1 mm), Cat. No.: 16-24 from Riegger    Industriehandel, Reinbek, Federal Republic of Germany-   E-copper ((100×20×1 mm), Cat. No.: 15-54 from Riegger-   diesel fuel to EN 590, with 5% (V/V) fatty acid methyl ester

Procedure: The solutions and the metal sheet were each introduced into a500 ml wide-neck bottle. Solutions 1A-1C were not stirred; solutions1D-1G were stirred with a magnetic stirrer. The appearance of thesolutions was assessed visually.

Sample Experiment Start After 4 weeks After 6 weeks 1A Cu sheet indiesel; without clear yellow clear yellow clear yellow stirring solutionsolution solution 1B Cu sheet in diesel + 500 ppm clear yellow clearyellow slightly turbid of 3,3′-methylenebis(5- solution solution yellowsolution methyloxazolidine); without stirring 1C Cu sheet in diesel + 50ppm clear yellow clear yellow turbid yellow of 3,3′-methylenebis(5-solution solution solution methyloxazolidine); without stirring 1D Cusheet in diesel; with clear yellow clear yellow clear yellow stirringsolution solution solution 1E Cu sheet in diesel + 500 ppm clear yellowclear yellow highly turbid of 3,3′-methylenebis(5- solution solutionsolution, some dark methyloxazolidine); with coating on the stirringsheet and at the base of the bottle 1F Cu sheet in diesel + 50 ppm clearyellow clear yellow clear yellow of 3,3′-methylenebis(5- solutionsolution solution, fluff in methyloxazolidine); with the solutionstirring 1G Brass sheet in diesel + clear yellow clear yellow turbidyellow 500 ppm of 3,3′- solution solution solution, some darkmethylenebis(5-methyl- coating on the oxazolidine); with stirring sheetand at the base of the bottle

Example 2 Materials Used

-   3,3′-methylenebis(5-methyloxazolidine)-   semiconcentrate 2: 20% 3,3′-methylenebis(5-methyloxazolidine), 0.9%    di-tert-butylphenol, 0.9% Irgamet 30; dissolved in ShellSol A 150-   E-copper (100×20×1 mm), Cat. No.: 15-54 from Riegger-   diesel fuel to EN 590, with 5% (V/V) fatty acid methyl ester content

Procedure: The solutions and the metal sheet were each introduced into a500 ml wide-neck bottle and stirred at room temperature with a magneticstirrer.

Sample 2A Diesel, stirred 2B Diesel + copper sheet, stirred 2C Diesel +500 ppm of 3,3′-methylenebis(5-methyloxazolidine); stirred 2D Diesel +copper sheet + 500 ppm 3,3′-methylenebis(5-methyloxazolidine) 2EDiesel + 2500 ppm of semiconcentrate 2, stirred 2F Diesel + coppersheet + 2500 ppm of semiconcentrate 2, stirred Copper content mg/l (ppm)2 days 1 week 2 weeks 3 weeks 6 weeks 2A 0.1 0.1 0.2 not determined 0.12B 1.3 1.5 1.8 1.6 2.3 2C 0.1 0.1 0.1 0.1 0.2 2D 0.6 0.6 0.8 1.0 1.0 2E0.1 <0.1 <0.1 <0.1 0.2 2F not determined 0.5 not determined 0.7 0.7Appearance 2A 2B 2C 2D 2E 2F Start clear yellow clear yellow clearyellow clear yellow clear yellow clear yellow solution solution solutionsolution solution solution after 1 week clear yellow clear yellow clearyellow clear yellow clear yellow clear yellow solution solution solutionsolution solution solution after 2 weeks clear yellow clear yellow clearyellow clear yellow clear yellow clear yellow solution solution solutionsolution solution solution after 3 weeks clear yellow clear yellow clearyellow clear yellow clear yellow clear yellow solution solution solutionsolution solution solution after 5 weeks clear yellow clear yellow clearyellow turbid yellow clear yellow clear yellow solution solution liquidsolution solution solution after 10 weeks clear yellow turbid yellowclear yellow red sludge at clear yellow clear yellow solution liquidsolution the base of a solution solution turbid yellow liquid after 11weeks clear yellow red sludge at clear yellow red sludge at clear yellowclear yellow solution the base of a solution the base of a solutionsolution turbid yellow turbid yellow liquid liquid after 12 weeks clearyellow red sludge at clear yellow red sludge at clear yellow clearyellow solution the base of a solution the bottom of solution solutionturbid yellow a turbid liquid yellow liquid after 13 weeks clear yellowred sludge at turbid red sludge at somewhat more somewhat more solutionthe base of a the base of a intense intense turbid yellow turbid yellowyellow yellow liquid liquid after 14 weeks clear yellow red sludge atturbid, a red sludge at somewhat more somewhat more solution the base ofa little brown the base of a intense intense turbid yellow sludge at theturbid yellow yellow yellow, brown liquid base liquid crumbs in thesolution after 15 weeks clear yellow red sludge at turbid, a red sludgeat somewhat more somewhat more solution the base of a little brown thebase of a intense intense turbid yellow sludge at the turbid yellowyellow yellow, brown liquid base liquid crumbs in the solution after 20weeks clear yellow red sludge at turbid, a red sludge at slightlyslightly solution the base of a little brown the base of a turbid,turbid, turbid yellow sludge at the turbid yellow somewhat more somewhatmore liquid base liquid intense intense yellow yellow, browncrumbs/fluff in the solution

Example 3 Materials Used

-   Concentrate X: 92% 3,3′-methylenebis(5-methyloxazolidine)+4% BHT+4%    benzotriazole-   Concentrate Y: 92% 3,3′-methylenebis(5-methyloxazolidine)+4%    2,6-di-tert-butylphenol+4% Irgamet 30-   E-copper (100×20×1 mm), Cat. No.: 15-54 from Riegger-   diesel fuel to EN 590, with 5% (V/V) fatty acid methyl ester content

Procedure: The solutions and the metal sheet were each introduced into a500 ml bottle and stirred with a magnetic stirrer.

Sample 3A Diesel + 500 ppm of concentrate X, stirred 3B Diesel + 500 ppmof concentrate X + copper sheet, stirred 3C Diesel + 500 ppm ofconcentrate Y, stirred 3D Diesel + copper sheet + 500 ppm of concentrateY; stirred Copper content mg/l (ppm) Blank value 3 weeks 6 weeks 3A 0.20.2 0.16 3B 0.2 1.4 2.1 3C 0.2 0.2 0.25 3D 0.2 0.7 0.67 Appearance 3A 3B3C 3D Start clear yellow clear yellow clear yellow clear yellow solutionsolution solution solution after 3 weeks clear yellow clear yellow clearyellow clear yellow solution solution solution solution after 6 weeksclear yellow clear yellow clear yellow clear yellow solution solutionsolution solution after 7 weeks clear yellow clear yellow clear yellowclear yellow solution solution solution solution after 8 weeks clearyellow clear yellow clear yellow clear yellow solution solution solutionsolution after 9 weeks clear yellow clear yellow clear yellow clearyellow solution solution solution solution after 10 clear yellowslightly clear yellow clear yellow weeks solution turbid, brown solutionsolution fluff after 11 clear yellow turbid, brown clear yellow clear,weeks solution sludge at the solution intensely base yellow solutionafter 12 clear yellow turbid, brown clear yellow clear, weeks solutionsludge at the solution intensely base yellow solution after 17 slightlyturbid, brown very slightly turbid, weeks turbid, sludge at the turbid,fluff/crumbs yellow base yellow in the solution

Example 4 Materials Used

-   3,3′-Methylenebis(5-methyloxazolidine)-   Semiconcentrate 4: 20% 3,3′-methylenebis(5-methyloxazolidine), 0.9%    di-tert-butylphenol, 0.9% Irgamet 30; dissolved in ShellSol A 150-   Diesel fuel to EN 590, with 5% (V/V) fatty acid methyl ester content-   Copper naphthenate (copper content: 7.97%; stock solution: 12.55 g    of copper naphthenate are dissolved/100 g of toluene, corresponding    to 1% copper)

Sample Test setup 4A Diesel 4B Diesel + 500 ppm of 3,3′-methylenebis(5-methyloxazolidine) 4C Diesel + 2500 ppm of semiconcentrate 4 4DDiesel + 1 ppm of copper + 500 ppm of 3,3′-methylenebis(5-methyloxazolidine) 4E Diesel + 5 ppm of copper + 500 ppm of3,3′-methylenebis (5-methyloxazolidine) 4F Diesel + 1 ppm of copper +2500 ppm of semiconcentrate 4 4G Diesel + 5 ppm of copper + 2500 ppm ofsemiconcentrate 4 4H Diesel + 1 ppm of copper (after 2 weeks) 4IDiesel + 5 ppm of copper (after 2 weeks)

All samples are stirred in a 250 ml screwtop bottle with a magneticstirrer at room temperature. The appearance changed as follows:

Appearance 4A 4B 4C 4D 4E 4F 4G 4H 4I Start clear yellow clear clearclear yellow clear clear clear solution yellow yellow solution yellowyellow yellow solution solution solution solution solution after clearyellow clear clear turbid turbid clear clear clear clear 2 weekssolution yellow yellow yellow yellow yellow yellow yellow yellowsolution solution liquid liquid solution solution solution solutionafter clear yellow clear clear turbid dark clear clear clear turbid 3weeks solution yellow yellow yellow sludge yellow yellow yellow yellowsolution solution liquid in solution solution solution liquid turbidyellow liquid after clear yellow clear clear dark sludge dark clearclear dark dark 4 weeks solution yellow yellow in turbid sludge yellowyellow sludge sludge in solution solution yellow in solution solution inturbid liquid turbid turbid yellow yellow yellow liquid liquid liquidafter clear yellow clear clear dark sludge dark clear turbid, dark dark5 weeks solution yellow yellow in turbid sludge yellow flocs sludgesludge in solution solution yellow in solution in turbid liquid turbidturbid yellow yellow yellow liquid liquid liquid after clear yellowclear clear dark sludge dark clear turbid, dark dark 6 weeks solutionyellow yellow in turbid sludge yellow flocs sludge sludge in solutionsolution yellow in solution in turbid liquid turbid turbid yellow yellowyellow liquid liquid liquid after clear yellow clear clear dark sludgedark turbid, turbid, dark dark 7 weeks solution yellow yellow in turbidsludge yellow, flocs sludge sludge in solution solution yellow in flocsin turbid liquid turbid turbid yellow yellow yellow liquid liquid liquidafter clear yellow clear clear dark sludge dark turbid, turbid, darkdark 12 weeks solution yellow yellow in turbid sludge yellow, flocssludge sludge in solution solution yellow in flocs in turbid liquidturbid turbid yellow yellow yellow liquid liquid liquid

Example 5 Materials Used

-   EL heating oil, low-sulfur (purely mineral, no fatty acid methyl    esters)-   Fatty acid methyl esters-   3,3′-Methylenebis(5-methyloxazolidine)-   Semiconcentrate X: 20% 3,3-methylenebis(5-methyloxazolidine), 0.9%    di-tert-butylphenol, 0.9% Irgamet 30; dissolved in ShellSol A 150-   E-copper (100×20×1 mm) Cat. No.: 15-4 from Riegger

Diesel sample Composition (% by vol.) 5A 100% heating oil + 0% biodiesel5B 90% heating oil + 10% biodiesel 5C 80% heating oil + 20% biodiesel 5D70% heating oil + 30% biodiesel Sample Experiment 5A1 5A + Cu 5A2 5A +500 ppm of 3,3-methylenebis (5-methyloxazolidine) 5A3 5A + 500 ppm of3,3-methylenebis (5-methyloxazolidine) + Cu 5A4 5A + 2500 ppm ofsemiconcentrate X 5A5 5A + 2500 ppm of semiconcentrate X + Cu 5B1 5B +Cu 5B2 5B + 500 ppm of 3,3-methylenebis (5-methyloxazolidine) 5B3 5B +500 ppm of 3,3-methylenebis (5-methyloxazolidine) + Cu 5B4 5B + 2500 ppmof semiconcentrate X 5B5 5B + 2500 ppm of semiconcentrate X + Cu 5C15C + Cu 5C2 5C + 500 ppm of 3,3-methylenebis (5-methyloxazolidine) 5C35C + 500 ppm of 3,3-methylenebis (5-methyloxazolidine) + Cu 5C4 5C +2500 ppm of semiconcentrate X 5C5 5C + 2500 ppm of semiconcentrate X +Cu 5D1 5D + Cu 5D2 5D + 500 ppm of 3,3-methylenebis(5-methyloxazolidine) 5D3 5D + 500 ppm of 3,3-methylenebis(5-methyloxazolidine) + Cu 5D4 5D + 2500 ppm of semiconcentrate X 5D55D + 2500 ppm of semiconcentrate X + Cu

The appearance of the individual sample changed as follows:

After After After After After After After Start 1 week 2 weeks 3 weeks 4weeks 5 weeks 6 weeks 11 weeks 5A1 clear red clear red clear red clearred clear red clear red clear red clear red solution solution solutionsolution solution solution solution solution 5A2 clear red clear redclear red clear red clear red clear red clear red clear, red, solutionsolution solution solution solution solution solution sediment on themetal and at the base 5A3 clear red clear red clear red clear red clearred clear red clear red Slightly solution solution solution solutionsolution solution solution turbid, sediment at the base 5A4 clear redclear red clear red clear red clear red clear red clear red clear redsolution solution solution solution solution solution solution solution5A5 clear red clear red clear red clear red clear red clear red clearred clear red solution solution solution solution solution solution, asolution, solution, a little fluff a little little fluff fluff 5B1 clearred clear red clear red clear red clear red clear red slightly slightlysolution solution solution solution solution solution, a turbid, turbid,little fluff crumbs crumbs 5B2 clear red clear red clear red clear redclear red clear red slightly slightly solution solution solutionsolution solution solution turbid, a turbid, a little little sedimentsediment at at the the base base 5B3 clear red turbid red dark sludgedark sludge dark sludge dark sludge dark dark sludge solution liquid inturbid in turbid in turbid in turbid sludge in in turbid red liquid redliquid red liquid red liquid turbid red red liquid liquid 5B4 clear redclear red clear red clear red clear red clear red slightly slightlysolution solution solution solution solution solution turbid, a turbid,a little little sediment sediment at at the the base base 5B5 clear redclear red clear red clear red clear red clear red slightly slightlysolution solution solution solution solution solution turbid, a turbid,a little little sediment sediment at at the the base base 5C1 clear redclear red clear red clear red clear red turbid turbid turbid, hassolution solution solution solution solution become lighter 5C2 clearred clear red clear red clear red clear red clear red slightly slightlysolution solution solution solution solution solution turbid, a turbid,a little little sediment sediment a at the the base base 5C3 clear redturbid red dark sludge dark sludge dark sludge dark sludge dark darksludge solution liquid in turbid in turbid in turbid in turbid sludge inin turbid red liquid red liquid red liquid red liquid turbid red redliquid liquid 5C4 clear red clear red clear red clear red clear redclear red slightly slightly solution solution solution solution solutionsolution turbid, a turbid, a little little sediment sediment at at thethe base base 5C5 clear red clear red clear red clear red clear redclear red slightly slightly solution solution solution solution solutionsolution turbid, a turbid, a little little sediment sediment at at thethe base base 5D1 clear red clear red clear red clear red clear redturbid turbid decolorized solution solution solution solution solutionto orange, turbid and sediment 5D2 clear red clear red clear red clearred clear red clear red slightly slightly solution solution solutionsolution solution solution turbid, a turbid, a little little sedimentsediment a at the the base base 5D3 clear red turbid red dark sludgedark sludge dark sludge dark sludge dark dark sludge solution liquid inturbid in turbid in turbid in turbid sludge in in turbid red liquid redliquid red liquid red liquid turbid red red liquid liquid 5D4 clear redclear red clear red clear red clear red clear red slightly slightlysolution solution solution solution solution solution turbid turbid 5D5clear red clear red clear red clear red clear red clear red slightlyslightly solution solution solution solution solution solution turbidturbid

EVALUATION OF THE EXAMPLES

Example 1 shows that 3,3′-methylenebis(5-methyloxazolidine) isincompatible as an additive to diesel oil (with 5% FAME) with a timedelay and in a concentration-dependent manner and more particularly inturbulent flow, when it comes into contact with copper or nonferrousmetal. 3,3-Methylenebis(5-methyloxazolidine) is thus, as an additive todiesel/biodiesel, associated with disadvantages when there is contactwith nonferrous metal. The biocide, which in principle has goodsuitability, is thus not very suitable owing to its incompatibility.

Example 2 shows that diesel fuel with 5% FAME can leach considerableamounts of copper salt out of copper sheet (2B). In the case of additionof 3,3′-methylenebis(5-methyloxazolidine), the copper wear is lower(2D), and in the case of addition of inventive semiconcentrate withShellSol A 150 significantly lower (2F). The formation of sludge in thesolution correlates with the amount of copper salt released. Even in theabsence of copper sheet, the performance of the inventivesemiconcentrate is somewhat better than that of3,3′-methylenebis(5-methyloxazolidine) (see 2E compared to 2C).

Example 3 shows that diesel fuel with 5% FAME in contact with coppersheet is protected better by addition of a concentrate composed of 92%3,3′-methylenebis(5-methyloxazolidine), 4% 2,6-di-tert-butylphenol and4% Irgamet 30 than by addition of a likewise inventive concentratecomposed of 92% 3,3′-methylenebis(5-methyloxazolidine), 4% BHT and 4%benzotriazole.

In Example 4, a defined amount of copper salt (copper naphthenate,dissolved in toluene) is added to diesel fuel with 5% FAME (4D to 41).WHEN 3,3′-methylenebis(5-methyloxazolidine) is added, there isincompatibility depending on the copper concentration (4D, 4E). Anaddition of inventive semiconcentrate significantly improves thestability of the diesel fuel (4F, 4G). Diesel fuel with 5% FAME leads,after addition of copper salt, to the formation of sludge (see 4H, 41).Diesel fuel with 5% FAME without addition of copper salt is stable (4A),and likewise in the case of addition of3,3′-methylenebis(5-methyloxazolidine) (4B) or inventive semiconcentrate(4C). This demonstrates that inventive semiconcentrates are alsosuitable for products which do not have a proportion of materialcomposed of renewable raw materials.

Example 5 shows the unfavourable influence of FAME (10 to 30% by volume)on diesel fuel when the latter is in contact with Cu. An addition of3,3′-methylenebis(5-methyloxazolidine) worsens the compatibility further(e.g. 5C3 compared to 5C1); only an addition of inventivesemiconcentrate gives a stable liquid in the presence of copper sheet(e.g. 5C5).

This shows that an N-formal such as3,3′-methylenebis(5-methyloxazolidine) is incapable of protectingFAME-containing liquids which are in contact with nonferrous metalsagainst microbial degradation. Only the combination with sufficientamounts of antioxidant and corrosion inhibitor leads to a product whichprotects FAME-containing liquids which are in contact with nonferrousmetals from microbial degradation. FAME-containing liquids are thenstorage-stable and do not form undesired precipitates.

1. An additive mixture for fuels, comprising: a) at least 80% by weightof at least one N-formal selected from the group consisting ofN,N′-methylenebis(4-methyloxazolidine),α,α′,α″-trimethyl-1,3,5-triazine-1,3,5-(2H,4H,6H)triethanol,4,4-dimethyloxazolidine, dimethylolurea,5-ethyl-3,7-dioxa-1-azabicyclo[3.3.0]octane,2-(hydroxymethylamino)ethanol, methylenebis(tetrahydro-1,3-bisoxazine),5-methylolchloro-acetamide, bis(hydroxymethyl)-5,5-dimethylhydantoin,diazolidinylurea, sodium hydroxymethylglycinate and3,4,4-trimethyloxazolidine,2,2′,2″-(hexahydro-1,3,5-triazine-1,3,5-triyl)triethanol,tetrahydro-1,3,4,6-tetrakis(hydroxylmethyl)imidazo[4,5-d]imidazole-2,5-(1H,3H)dione(TMAD) and tetramethylolglycoluril, b) at least 1% by weight of at leastone antioxidant selected from the group consisting of stericallyhindered phenols, amines, vitamin E and derivatives thereof, and alkylgallates, and c) at least 1% by weight of at least one corrosioninhibitor selected from the group consisting of benzotriazole,tolyltriazole and N,N-bis(2-ethylhexyl)((1,2,4-triazol-1-ylmethyl)amine,wherein the weight ratio of component b) to component c) is 1:10 to10:1.
 2. The additive mixture according to claim 1, wherein the N-formalis N,N′-methylenebis(5-methyloxazolidine).
 3. The additive mixtureaccording to claim 1, wherein the antioxidant is selected from the groupconsisting of 3-tert-butyl-4-hydroxyanisole (BHA),2,6-di-tert-butyl-p-cresol (BHT), 2,6-di-tert-butylphenol, laurylgallate and Vitamin E.
 4. The additive mixture according claim 1,wherein the corrosion inhibitor isN,N-bis(2-ethylhexyl)((1,2,4-triazol-1-yl)methyl)amine.
 5. The additivemixture according to claim 1, wherein the weight ratio of component b)to component c) is 1:4 to 4:1.
 6. The additive mixture according toclaim 1, wherein said additive mixture is a liquid concentrate, and thecomponent a) is at least 90% by weight of said additive mixture.
 7. Theadditive mixture according to claim 1, wherein said additive mixture isa liquid concentrate and the components b) and c) are each at least 2%by weight of said additive mixture.
 8. The additive mixture according toclaim 1, comprising a) at least 90% by weight ofN,N′-methylenebis(5-methyloxazolidine), b) at least 2% by weight of atleast one antioxidant selected from 2,6-di-tert-butylphenol and BHT, andc) at least 2% by weight ofN,N-bis(2-ethylhexyl)((1,2,4-triazol-1-ylmethyl)amine, wherein theweight ratio of component b) to component c) is 1:4 to 4:1.
 9. A methodof biocidal and corrosion-inhibiting additization of a fuel that flowsor is stored in a system comprising copper-containing material incontact with said fuel comprising adding to said fuel the additivemixture according to claim 1.